I took a look on the Mayhem Forums to see what you were talking about and in one of the 100 threads about who the replacement might be one guy legitimately thought Black Sabbath was the replacement.

Exactly. Bands that are in the same demographic as far as modern day success as HoF would be Chimaira, Shadows Fall, Crowbar, Bleeding Through, Skeletonwitch or Prong. I believe, depending on their summer touring schedule - which I have zero knowledge of, that Shadows Fall and Chimaira are at the top of their 'replacement' list.